Recording apparatus having skew removal

ABSTRACT

A recording apparatus has a paper feeder wherein single sheets of paper can be set, a paper delivery device for transporting paper fed from the paper feeder to a recorder, and a control unit for controlling operation of the paper feeder and the paper delivery device. The control unit has a skew removal execution mode of only the first sheet of paper where the paper tip is bitten into a paper delivery roller forming a part of the paper delivery device and then the paper delivery roller is reversely rotated for ejecting the paper tip for the first sheet of paper at the start of recording and then forward rotating the paper delivery roller for delivering the sheet of paper whose skew is removed to the recorder and delivering the second and later sheets of paper to a record area without executing the skew removal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 10/230,374, filedAug. 29, 2002, which is incorporated herein by reference in itsentirety.

DETAILED DESCRIPTION OF THE INVENTION

1. Field of the Invention

This invention relates to a recording apparatus comprising a paperfeeder for stacking a plurality of record materials and feeding themdownstream one at a time from the top record material.

2. Related Art

A printer is available as one of recording apparatus and some printerscomprise a paper feeder for feeding print paper as record materialdownstream one sheet at a time. Further, such a paper feeder comprises apaper feed roller which is rotated and a hopper made of a plate-likebody long in the width direction of print paper, placed in an inclinedattitude with the paper feed passage of print paper as a side view,comprising a rotation support point in an upper part, and rotated,thereby being brought away from and pressed against the paper feedroller, and pushes up stacked sheets of print paper by the hopper,thereby feeding print paper one sheet at a time from the top sheet.

The hopper is urged by an urging device and is rotated in a direction inwhich it is pressed against the paper feed roller, whereby stacked printpaper is pressed against the paper feed roller. The hopper comprises arelease device and is rotated in a direction in which it is brought awayfrom the paper feed roller, and is held by the release device. Thus, thehopper is displaced between the paper feed position for pressing the topsheet of print paper against the paper feed roller (paper feed state)and the standby position at which the hopper is most away from the paperfeed roller (release state). The paper feed position changes dependingon the number of set (stacked) sheets of print paper.

By the way, when the hopper is displaced from the standby position tothe paper feed position, it is rotated vigorously in the direction inwhich the hopper is pressed against the paper feed roller by the urgingforce of the urging device and therefore print paper collides with thepaper feed roller and thus there is a problem of producing large noise(collision noise) from the components in the surroundings of the hopperand the paper feed roller.

The rotation angle (swing angle) of the hopper to displace the hopperfrom the standby position to the paper feed position changes dependingon the number of set (stacked) sheets of print paper as described above.That is, the larger the number of sheets of print paper, the smaller theswing angle; the smaller the number of sheets of print paper, the largerthe swing angle. Therefore, if the number of set sheets of paper issmall, the swing angle of the hopper becomes large and thus it takestime in the paper feed operation and paper cannot be repeatedly fed athigh speed; this is a problem.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to decrease noise occurringwhen a hopper is swung and make it possible to perform high-speed paperfeed operation.

(1) According to the invention, there is provided a recording apparatuscomprising:

a paper feeder configured to set a plurality of single sheets of papertherein;

a paper delivery device having a paper delivery roller for transportinga sheet of paper fed from said paper feeder to a recorder; and

a control unit for controlling operation of said paper feeder and saidpaper delivery device;

wherein said paper feeder and paper delivery device are configured toconduct a skew removal that a paper tip of a sheet of paper fed fromsaid paper feeder is once bitten into the paper delivery roller and thenejected therefrom by reversely rotating said paper delivery rollerbefore delivering the sheet of paper to the recorder by forwardlyrotating the paper delivery roller; and

said control unit comprises a skew removal execution mode of only thefirst sheet of paper where the skew removal is executed only to a papertip of a first sheet of paper which is firstly fed by the paper feederat a start of recording operation of the apparatus and later sheets ofpaper are delivered to the recorder without executing the skew removal.

To execute one job for recording on a plurality of sheets of paper set(stacked) in the paper feeder, the paper is fed in the order of thefirst sheet, the second sheet, the third sheet . . . and further apredetermined amount of start locating control is performed in the paperdelivery device and then the paper is delivered to the recorder forrecording on the paper. At the time, the first sheet of paper is fedfrom the nonoperating state (incomplete warming-up state) in which paperis placed in the standby state in the paper feeder and on the otherhand, the second and later sheets of paper are fed from the operationcontinuation state (complete warm-up state) just after the paper feederonce performs the paper feed operation. There is a tendency of easyoccurrence of a problem of paper feed (delivery) accuracy degradationsuch that the paper tip position accuracy of the first sheet of paper isdegraded more easily than that of the second or later sheet of paperbecause of the difference.

According to the above (1), the skew removal is performed only for thefirst sheet of paper whose feed (delivery) accuracy is easily degraded,so that the predetermined amount of start locating control, etc., can beaccomplished with high accuracy and degradation of paper feed accuracycan be prevented easily. Moreover, the skew removal is not performed forthe second or later sheet of paper whose feed (delivery) accuracy ishard to degrade, so that the paper feed accuracy can be secured and thethroughput can be enhanced in all process of one job from record startto end.

(2) The invention is further characterized by the feature that in therecording apparatus of (1), said paper feeder includes a paper feedroller for feeding one of the sheets of paper by rotating and a hopperfor pushing up and pressing the sheets of paper against the paper feedroller, and

the hopper is configured to push up the first sheet of paper at thestart of recording operation at a first stroke and to push up the latersheets of paper at a second stroke which is smaller than the firststroke.

With the hopper configured so as to push up the first sheet of paper atthe start of recording at a large stroke and push up the second andlater sheets of paper at a smaller stroke than the large stroke,particularly the paper feed (delivery) accuracy of the first sheet ofpaper is easily degraded and thus the invention is applied and theadvantage is noticeable.

As a specific structure example of the large stroke and the smallerstroke, the following configuration is possible: Release device forbringing the hopper away from the paper feed roller comprises the threehopper control modes: A non-release mode, a large release mode, and asmall release mode positioned therebetween.

In the non-release mode, the release device does not give any externalforce to the hopper and allows the record material to be pressed againstthe paper feed roller by the urging force of urging device. That is, inthe non-release mode, the hopper is at the paper feed position (in thepaper feed state).

Next, in the large release mode, the hopper is rotated so that it isbrought most away from the paper feed roller, and is held in this state.That is, in the large release mode, the hopper is at complete standbyposition (release state) and in the state, it is made possible to setrecord material.

The paper feeder comprises the small release mode in which the hopperposition is between the non-release mode and the large release mode.That is, in the small release mode, the hopper is rotated and is held sothat the top record material is brought a little away from the paperfeed roller. Therefore, when the hopper is rotated for the paper feedoperation of the next record material from the state, the rotation angle(swing angle) of the hopper to press the record material against thepaper feed roller can be minimized. For example, if the small releasemode is executed when the paper feed job is followed by another paperfeed job, it is made possible to decrease noise occurring when therecord material is pressed against the paper feed roller, and executethe high-speed paper feed operation (repeated paper feed).

(3) According to the invention, there is provided a recording apparatuscomprising:

a paper feeder configured to set a plurality of single sheets of papertherein;

a paper delivery device having a paper delivery roller for transportinga sheet of paper fed from said paper feeder to a recorder; and

a control unit for controlling operation of said paper feeder and saidpaper delivery device;

wherein said paper feeder and paper delivery device are configured toconduct a skew removal that a paper tip of a sheet of paper fed by saidpaper feeder is once bitten into the paper delivery roller and thenejected therefrom by reversely rotating said paper delivery rollerbefore delivering the sheet of paper to the recorder by forwardlyrotating the paper delivery roller; and

said control unit comprises a skew removal mode where the skew removalis executed to a sheet of paper whose margin dimension in data toexecute recording is smaller than a reference value and a skew removalsuppression mode where a sheet of paper whose margin dimension is largerthan the reference value is delivered to the recorder without executingthe skew removal.

To print up to the margin of paper, if a skew exists, it is conspicuous;on the other hand, in printing on paper with a comparatively largemargin, if a small skew exists, it is hard to be conspicuous. Accordingto the invention, only when printing up to the margin of paper, the skewremoval mode is applied and in printing on paper with a comparativelylarge margin, the skew removal suppression mode is applied, so that inprinting on paper with a comparatively large margin, enhancement ofthroughput can take precedence over.

(4) According to the invention, there is provided a recording apparatuscomprising:

a paper feeder configured to set a plurality of single sheets of papertherein;

a paper delivery device having a paper delivery roller for transportinga sheet of paper fed from said paper feeder to a recorder; and

a control unit for controlling operation of said paper feeder and saidpaper delivery device;

wherein said paper feeder and paper delivery device are configured toconduct a skew removal that a paper tip of a sheet of paper fed by saidpaper feeder is once bitten into the paper delivery roller and thenejected therefrom by reversely rotating said paper delivery rollerbefore delivering the sheet of paper to the recorder by forwardlyrotating the paper delivery roller; and

said control unit comprises a skew removal mode where the skew removalis executed to a sheet of paper whose image data amount in data toexecute recording is larger than a reference value and a skew removalsuppression mode where a sheet of paper whose image data amount issmaller than the reference value is delivered to the recorder withoutexecuting the skew removal.

According to the invention, the control unit comprises the skew removalmode for executing skew removal and then delivering the paper to therecorder when the image (print) data amount in data to execute recordingis larger than the reference value and the skew removal suppression modefor delivering the paper to the recorder without executing skew removalwhen the image data amount is smaller than the reference value, so thatwhen the amount of image data with a skew hard to be conspicuous issmall, throughput can be enhanced.

(5) According to the invention, there is provided a recording apparatuscomprising:

a paper feeder configured to set a plurality of single sheets of papertherein, including a paper feed roller for feeding one of the sheets ofpaper by rotating and a hopper for pushing up and pressing the sheets ofpaper against the paper feed roller;

a paper delivery device having a paper delivery roller for transportinga sheet of paper fed from said paper feeder to a recorder; and

a control unit for controlling operation of said paper feeder and saidpaper delivery device;

wherein the hopper is configured to push up the first sheet of paper atthe start of recording operation at a first stroke and to push up thelater sheets of paper at a second stroke which is smaller than the firststroke; and

said control unit comprises a speed change mode where a first hopperpushing-up speed when the first stroke is applied is set lower than asecond pushing-up speed when the second stroke is applied.

When the large stroke is applied, the hopper swing distance is large andthus noise when paper is pressed against the paper feed roller becomeseasily large. However, according to the invention, the control unitcomprises the speed change mode for setting the hopper pushing-up speedwhen the large stroke is applied lower than the pushing-up speed whenthe smaller stroke is applied, so that the noise problem can be solvedefficiently and the whole throughput of one print job can be enhanced.

(6) According to the invention, there is provided a recording apparatuscomprising:

a paper feeder configured to set a plurality of single sheets of papertherein;

a paper delivery device for transporting paper fed from said paperfeeder to a recorder; and

a control unit for controlling operation of said paper feeder and saidpaper delivery device;

wherein said control unit comprises two or more of the modes in therecording apparatus according to any of (1) to (5).

According to the invention, the optimum paper feed mode can be selectedfor execution in one print job for different types of paper anddifferent-size paper.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description ofthe presently preferred exemplary embodiments of the invention taken inconjunction with the accompanying drawings, in which:

FIG. 1 is an external perspective view of a printer main unit of an inkjet printer according to the invention;

FIG. 2 is an exploded perspective view of the printer main unit of theink jet printer according to the invention;

FIG. 3 is a sectional side view of the ink jet printer according to theinvention;

FIG. 4 is a front view of the printer main unit of the ink jet printeraccording to the invention;

FIG. 5 is a perspective view of a paper feeder according to theinvention;

FIG. 6 is a front view of the paper feeder according to the invention;

FIG. 7 is a sectional side view of the paper feeder according to theinvention;

FIGS. 8A and 8B are a side view and a front view of a paper feed rollerand a paper feed auxiliary roller;

FIGS. 9A and 9B are schematic representations of a rush angle of paper Pinto a separation pad 8 (partially enlarged view of FIG. 7);

FIG. 10 is a perspective view (partially enlarged view) of the paperfeeder according to the invention;

FIG. 11 is a schematic drawing to show the action position of anexternal force acting on a hopper 6;

FIG. 12A is a front view of a rotary cam and FIG. 12B is a sectionalview taken on line y-y in FIG. 12A;

FIG. 13A is a front view of a cam lever holder and FIG. 13B is a sideview of the cam lever holder;

FIG. 14 is a timing chart to show the operation transition of a paperfeed roller, a cam lever, and a hopper;

FIGS. 15A and 15B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 15A showsthe positional relationship between the paper feed roller and the hopperand FIG. 15B shows the engagement state of the cam lever and the rotarycam;

FIGS. 16A and 16B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 16A showsthe positional relationship between the paper feed roller and the hopperand FIG. 16B shows the engagement state of the cam lever and the rotarycam;

FIGS. 17A and 17B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 17A showsthe positional relationship between the paper feed roller and the hopperand FIG. 17B shows the engagement state of the cam lever and the rotarycam;

FIGS. 18A and 18B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 18A showsthe positional relationship between the paper feed roller and the hopperand FIG. 18B shows the engagement state of the cam lever and the rotarycam;

FIGS. 19A and 19B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 19A showsthe positional relationship between the paper feed roller and the hopperand FIG. 19B shows the engagement state of the cam lever and the rotarycam;

FIGS. 20A and 20B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 20A showsthe positional relationship between the paper feed roller and the hopperand FIG. 20B shows the engagement state of the cam lever and the rotarycam;

FIGS. 21A and 21B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 21A showsthe positional relationship between the paper feed roller and the hopperand FIG. 21B shows the engagement state of the cam lever and the rotarycam; and

FIGS. 22A and 22B are schematic representations during the paper feedoperation of the paper feeder according to the invention; FIG. 22A showsthe positional relationship between the paper feed roller and the hopperand FIG. 22B shows the engagement state of the cam lever and the rotarycam.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, there is shown a preferredembodiment of the invention in the order of “General configuration ofink jet printer,” “General configuration of paper feeder,” and“Configuration of hopper release device.”

<General Configuration of Ink Jet Printer>

The general configuration of an ink jet printer according to oneembodiment of the invention will be discussed with reference to FIGS. 1to 4. FIG. 1 is an external perspective view of a printer main unit ofthe ink jet printer (simply, printer) 100, FIG. 2 is an explodedperspective view of the printer main unit of the printer, FIG. 3 is asectional side view of the printer main unit of the printer, and FIG. 4is a front view of the printer main unit of the printer.

In FIGS. 1 and 2, the printer main unit of the printer 100 is dividedinto a plurality of units and the units are combined into the printermain unit. In the figures, numeral 1 denotes a paper feed unit as apaper feeder capable of feeding paper P (see FIG. 3) or roll paper (notshown) as record material, numeral 120 denotes a carriage unitcomprising a carriage 122 having an ink jet record head 124 (see FIG.3), numeral 160 denotes a transport unit for transporting the paper P,and numeral 180 denotes an ink system unit for maintaining the ink jetrecord head 124. The printer main unit of the printer 100 is dividedinto the four units as shown in FIG. 2 and the four units are combinedinto the printer main unit as shown in FIG. 1. In the embodiment, thecarriage unit 120 and the ink system unit 180 are joined to the top andthe right (in FIG. 4) of the transport unit 160 respectively and thepaper feed unit 1 is joined to the rear of the carriage unit 120,whereby the four units are combined into the printer main unit.

Next, the paper transport passage of the printer 100 will be discussedwith reference to FIG. 3. Hereinafter, the left of FIG. 3 (the rear ofthe printer 100) will be referred to as “upstream” and the right of FIG.3 (the front of the printer 100) will be referred to as “downstream.”The printer 100 comprises a hopper 6 placed upstream for stacking sheetsof paper P as single sheets of paper on the hopper 6 in an inclinedattitude. The hopper 6 is placed rotatably clockwise andcounterclockwise in FIG. 3 with a rotation shaft 6 a (see FIG. 7)positioned in an upper part as the center. As the hopper 6 rotates, alower part of the hopper 6 is pressed against and is brought away from apaper feed roller 3. The hopper 6 also comprises a moving guide 4slidable in the width direction of the paper P (see FIG. 1) for guidingthe side end of each of stacked sheets of the paper P together with afixed guide 5 (see FIG. 1). The top one of the stacked sheets of thepaper P is paid out downstream as the hopper 6 is pressed against thepaper feed roller 3 and the paper feed roller 3 is rotated in the pressstate. The paper feed roller 3 is shaped roughly like a letter D as aside view. At the print operation time, the paper feed roller 3 iscontrolled so that a flat portion of the paper feed roller 3 is opposedto the paper P (state in FIG. 3), thereby preventing transport load ofthe paper P from occurring.

The length of a circular arc portion of the paper feed roller 3 is setto a length to allow the paper P to be paid out from the top of thehopper 6 and the tip of the paid-out paper P to arrive at a nip pointbetween a transport drive roller 162 and a transport driven roller 163,namely, is set equal to or more than the paper feed passage length fromthe press contact between the paper feed roller 3 and the paper P to thenip point between the transport drive roller 162 and the transportdriven roller 163. Therefore, for example, to enable a larger number ofsheets of paper P to be stacked on the hopper 6 in FIG. 3, the placementposition of the paper feed roller 3 needs to be moved upward (to theupper left) in FIG. 3. In such a case, the diameter of the paper feedroller 3 is made large (in the embodiment, 48 mm), whereby it is madepossible to cope with change in the paper feed passage lengthaccompanying the upward move of the placement position of the paper feedroller 3.

Next, a paper guide 167 as a plate-like body is placed roughlyhorizontally on the downstream bottom from the paper feed roller 3. Thetip of the paper P to be paid out by the paper feed roller 3 abuts thepaper guide 167 slantingly and is moved smoothly downstream. Placeddownstream from the paper guide 167 are the transport drive roller 162which is rotated and the transport driven roller 163 pressed against thetransport drive roller 162. The paper P is nipped between the transportdrive roller 162 and the transport driven roller 163 and is transporteddownstream at a constant pitch.

The transport driven roller 163 is journaled by a transport drivenroller holder 164 downstream thereof. The transport driven roller holder164 is placed rotatably clockwise and counterclockwise in FIG. 3 with arotation shaft 164 a as the center and is urged for rotation by atorsion coil spring (not shown) in a direction in which the transportdriven roller 163 is always pressed against the transport drive roller162 (clockwise in FIG. 3).

Next, a paper detector 136 consisting of a sensor main unit 136 b and adetector 136 a for detecting passage of the paper P is disposed in theproximity of the transport driven roller holder 164 positioned most tothe 0 digit side (the right front of FIG. 2). The detector 136 a isshaped roughly like V as a side view and is placed rotatably clockwiseand counterclockwise in FIG. 2 with a rotation shaft 136 c in the centervicinity of the detector 136 a as the center. The sensor main unit 136 bpositioned above the detector 136 a comprises a light emission section(not shown) and a light reception section (not shown) for receivinglight from the light emission section. The upper side of the detector136 a from the rotation shaft 136 c shuts off the light emitted from thelight emission section to the light reception section and allows thelight to pass through as it is rotated. Therefore, if the detector 136 ais rotated so as to be pushed upward with the passage of the paper P asshown in FIG. 3, the upper side of the detector 136 a is detached fromthe sensor main unit 136 b and accordingly the light reception sectionreceives light, so that the passage of the paper P is detected.

Next, a platen 166 and the ink jet record head 124 are disposeddownstream from the transport drive roller 162 so that they arevertically opposed to each other. The platen 166 is long in a mainscanning direction (see FIG. 2). The paper P transported to below theink jet record head 124 as the transport drive roller 162 rotates issupported by the platen 166 from below the paper P. The ink jet recordhead 124 is placed on the bottom of the carriage 122 on which an inkcartridge 123 is mounted. The carriage 122 reciprocates in the mainscanning direction while it is guided by a carriage guide shaft 125extending in the main scanning direction. In the embodiment, the inkcartridge 123 comprises four separate color ink cartridges (black,yellow, cyan, and magenta ink cartridges) as shown in FIG. 4, and thefour ink cartridges can be replaced separately.

Next, a paper ejection section of the printer 100 is formed downstreamfrom the ink jet record head 124, and paper ejection drive rollers 165,a paper ejection driven roller 131, and a paper ejection auxiliaryroller 132 are disposed. A plurality of paper ejection drive rollers 165are attached to a rotated paper ejection drive roller shaft 165 a overthe axial direction thereof (see FIG. 4). The paper ejection drivenroller 131 journaled by a paper ejection driven roller holder 131 aattached to a paper ejection frame 130 is pressed lightly against thepaper ejection drive roller 165, whereby it is driven and rotated.Therefore, the paper P printed by the ink jet record head 124 is ejectedin a paper ejection direction (arrow direction in FIG. 3) as the paperejection drive rollers 165 are rotated in a state in which the paper Pis nipped between the paper ejection drive rollers 165 and the paperejection driven roller 131. The paper ejection auxiliary roller 132journaled by a paper ejection auxiliary roller holder 132 a is placed alittle upstream from the paper ejection driven roller 131 for preventingthe paper P from floating up from the platen 166 so as to a little pressdownward the paper P, thereby regulating the distance between the paperP and the ink jet record head 124.

The hopper 6, the moving guide 4, the fixed guide 5, and the paper feedroller 3 described above are placed in the above-described paper feedunit 1 shown in FIGS. 1 and 2. The paper feed unit 1 has a base made ofa paper feed unit frame 2 comprising a right attachment part 2 a and aleft attachment part 2 b each shaped roughly like a pillar, placedupright at the left and the right with the hopper 6 between, as shown inFIG. 2. The hopper 6, a paper feed roller shaft 3 a of a rotation shaftof the paper feed roller 3, and the like are placed on the paper feedunit frame 2. The paper feed unit 1 is joined to the rear of thecarriage unit 120 in the upper parts of the attachment part 2 a and theattachment part 2 b. The more detailed configuration of the paper feedunit 1 will be discussed later.

Next, the paper guide 167, the transport drive roller 162, the transportdriven roller holder 164, and the paper ejection drive roller shaft 165a are placed in the transport unit 160 shown in FIGS. 1 and 2. Thetransport unit 160 has a base made of a transport unit frame 161 shapedroughly like angular U as a plan view, as shown in FIG. 2. The transportunit 160 comprises a power unit 168 of a power supply section of theprinter 100 on the rear, journals the paper ejection drive roller shaft165 a on the front and the transport drive roller 162 almost at thecenter, and comprises the platen 166 in an upper front part and thetransport driven roller holder 164 in an upper center. The transportunit 160 also comprises a drive motor 169 (see FIG. 4) of a common drivesource to the paper feed roller 3, the transport drive roller 162, thepaper ejection drive rollers 165, a pump unit 182 (described later), anda blade unit 184 (described later) in a lower left part. The drive motor169 and the five types of components to be driven by the drive motor 169are joined by a power transmission mechanism (not shown) and thecomponents can be selectively driven in the state in which the fourunits are combined as shown in FIG. 1.

The ink system unit 180 as a maintenance device of the ink jet recordhead 124, joined to the right side of the transport unit 160 comprises aframe 181 as the base of the ink system unit 180, joined to the rightside of the transport unit frame 161, and comprises a cap unit 183, thepump unit 182, and the blade unit 184 on the frame 181, as shown in FIG.2. When the carriage 122 moves to a home position (right area of FIG.4), the cap unit 183 caps the ink jet record head 124 to protect anozzle face (not shown) and the pump unit 182 supplies a negativepressure to the cap unit 183 in the cap state for sucking ink throughnozzle openings of the ink jet record head 124. The blade unit 184 canbe moved between a position crossing the reciprocating area of thecarriage 122 and a position retreating from the reciprocating area. Theblade unit 184 is moved to the position crossing the reciprocating areaof the carriage 122 and the carriage 122 is moved from a print area tothe home position (right area of FIG. 4) or from the home position tothe print area, whereby the nozzle face (not shown) of the ink jetrecord head 124 is wiped for cleaning.

The carriage guide shaft 125 and the paper detector 136 are placed inthe carriage unit 120. The carriage unit 120 has a base made up of amain frame 121 a and a right side frame 121 b and a left side frame 121c placed upright on both sides of the main frame 121 a, and journals thecarriage guide shaft 125 on the rear, as shown in FIG. 2.

As shown in FIG. 4, the carriage unit 120 comprises a carriage motor 127on the left rear, and a drive pulley 128 is attached to the carriagemotor 127. The carriage unit 120 comprises a driven pulley 129 at theright. A carriage belt 126 is placed on the drive pulley 128 and thedriven pulley 129 and a part of the carriage belt 126 is fixed to thecarriage 122. Therefore, the carriage 122 is reciprocated in the mainscanning direction (from side to side in FIG. 4) as the carriage motor127 is turned.

In FIG. 2, the paper ejection frame 130 is attached to the carriage unit120, but can be attached not only to the carriage unit 120, but also tothe transport unit 160.

The description of the configuration of the printer main unit of theprinter 100 is now complete. The four units are combined and joined,whereby the printer 100 can be operated.

<Detailed Configuration of Paper Feed Unit>

Next, the detailed configuration (general configuration) of the paperfeed unit 1 will be discussed with reference to FIGS. 5 to 9B. FIG. 5 isan external perspective view of the paper feed unit 1, FIG. 6 is a frontview of the paper feed unit 1, FIG. 7 is a sectional side view of thepaper feed unit 1, FIGS. 8A and 8B are a side view and a front view ofthe paper feed roller 3 and a paper feed auxiliary roller 15, and FIGS.9A and 9B are a schematic representation of a rush angle of paper P intoa separation pad 8 (partially enlarged view of FIG. 7).

To begin with, the paper feed unit 1 has the base made of the paper feedunit frame 2 as described above and comprises a transmission gear unit17 on the left side of the paper feed unit frame 2 (the left of FIG. 6),a hopper release device consisting of a rotary cam 20, etc., (describedlater) on the right side of the paper feed unit frame 2 (the right ofFIG. 6), and a paper feed roller shaft 3 a placed therebetween.

The transmission gear unit 17 meshes with a transmission gear (notshown) of the transport unit 160 in a state in which the paper feed unit1 is joined to the carriage unit 120 (see FIG. 1), and transmitsrotation force of the drive motor 169 (see FIG. 4) attached to thetransport unit 160 to the paper feed roller shaft 3 a. Therefore, thepaper feed unit 1 (paper feed roller shaft 3 a) uses the drive motor 169of the drive source of the transport drive roller 162, etc., as thepower source and thus does not have its own drive source, so that thepaper feed unit 1 is formed at low cost. The paper feed roller shaft 3 atransmits the rotation force given to the left end by the transmissiongear unit 17 to the hopper release device (described later) placed atthe right end. Therefore, the paper feed roller shaft 3 a in theembodiment serves not only a function as the rotation shaft of the paperfeed roller 3, but also a function as the power transmission shaft.

The paper feed roller 3 rotated by the paper feed roller shaft 3 a isplaced at the right end, namely, at a position at a distance from thetransmission gear unit 17 as shown in FIG. 6. The paper feed roller 3 isshaped roughly like a letter D as a side view as mentioned above and ismade up of a roller main body 3 c resin-molded integrally with the paperfeed roller shaft 3 a and a rubber member 3 b as an “elastic member”wound around the outer peripheral portion of the roller main body 3 c,as shown in FIGS. 5 and 7. The rubber member 3 b provides a frictioncoefficient with the paper P, so that the paper P pressed against thepaper feed roller 3 is reliably fed without slip. In the embodiment,EPDM (ethylene propylene rubber) is used as the rubber member 3 b. Apaper feed auxiliary roller 15 shaped roughly like a letter D as a sideview in the axial direction is placed on the paper feed roller shaft 3 abetween the left end of the paper feed roller shaft 3 a and the paperfeed roller 3; it will be discussed later in detail.

Next, the hopper 6 made of a plate-like body long in the width directionof the paper P is placed in the paper feed unit 1 in an inclinedattitude as shown in FIG. 7. The hopper 6 is placed rotatably clockwiseand counterclockwise in FIG. 7 with the rotation shaft 6 a as thecenter, as described above, and a helical compression spring 7 as“urging device” for urging the lower part of the hopper toward the paperfeed roller 3 is placed in a lower part of the rear of the hopper 6, sothat the hopper 6 is always urged and rotated in a direction in which itis pressed against the paper feed roller 3. The paper feed unit 1comprises “hopper release device” for rotating the hopper 6 in adirection in which the hopper 6 is brought away from the paper feedroller 3. The configuration and function of the hopper release devicewill be discussed later in detail.

Next, a separation pad holder 9 and a guide member 13 are placed belowthe hopper 6. The separation pad holder 9 is placed at a positionopposed to the paper feed roller 3 as shown in FIG. 6 and holds aseparation pad 8 made of a frictional member so that the separation pad8 is opposed to the paper feed roller 3 as shown in FIG. 7. Theseparation pad holder 9 is placed rotatably clockwise andcounterclockwise in FIG. 7 with a rotation shaft 9 a as the center, andis urged and rotated by a helical compression spring 10 in a directionin which the separation pad 8 is pressed against the paper feed roller3. Therefore, if the paper feed roller 3 is rotated from the state shownin FIG. 7 (in which the separation pad 8 and the flat portion of thepaper feed roller 3 face each other), the separation pad 8 is pressedagainst the circular arc portion of the paper feed roller 3.

The top sheet of paper P abutted against (rushed into) the separationpad 8 placed in the separation pad holder 9 at abutment angle α issandwiched between the separation pad 8 and the paper feed roller 3,thereby preventing duplicate delivery of the next sheet of paper P. Moreparticularly, letting the friction coefficient between the paper feedroller 3 and paper P be μ1, the friction coefficient between sheets ofpaper P be μ2, and the friction coefficient between paper P and theseparation pad 8 be μ3, the materials of the rubber member 3 b and theseparation pad 8 are selected so that the relation μ1>μ3>μ2 holds.Therefore, the top sheet of paper P to be fed is paid out reliablydownstream with rotation of the paper feed roller 3 and the next sheetof paper P remains on the separation pad 8, so that duplicate deliveryof paper P is prevented. In a lower part of the hopper 6, a retentionpad 6 b is placed at a position opposed to the paper feed roller 3 andthe paper feed auxiliary roller 15 (described later) for retaining abundle of sheets of paper P retained on the hopper 6 so that the entirebundle is not moved downstream when the top sheet of paper P is fed.

By the way, the fluctuation range of the abutment angle α in theembodiment, namely, the placement position of the rotation shaft 6 adetermining the swing angle of the hopper 6 and the feed directiondimension of the hopper 6 (length direction dimension of paper P) areset as follows: The angle at which the hopper swings from the state inwhich the hopper 6 is most away from the paper feed roller 3 to thestate in which the top sheet of paper P is pressed against the paperfeed roller 3 changes depending on the number of sheets of paper Pstacked on the hopper 6 and accordingly the abutment angle α at whichthe paper P tip abuts the separation pad 8 also changes. FIGS. 9A and 9Bshow the angle; FIG. 9A shows abutment angle α_(max) when the number ofset sheets of paper P is the maximum and FIG. 9B shows abutment angleα_(min) when the number of set sheets of paper P is almost the minimum.As seen in the figures, the larger the number of set sheets of paper P,the larger the abutment angle α. In FIGS. 9A and 9B, numeral P₁indicates the top sheet of paper and numeral P₂ indicates the next sheetof paper to the sheet P₁ of paper.

However, in FIG. 9A, when the abutment angle α_(max) becomes larger thanthe maximum value α₁ of the abutment angle at which the top sheet ofpaper P can pass through, the top sheet P₁ of paper to be fed is caughtin the separation pad 8 and may not be fed. In contrast, when theabutment angle α_(min) becomes smaller than the minimum value α₂ of theabutment angle at which duplicate delivery of sheets of paper P can beprevented, the next sheet P₂ of paper (or a plurality of sheets of paperP on and after the sheet P₂ of paper) is inserted between the sheet P₁of paper to be fed and the separation pad 8 and duplicate delivery ofthe sheets of paper may occur. Then, in the embodiment, the placementposition of the rotation shaft 6 a of the hopper 6 and the feeddirection dimension of the hopper 6 are set so that the abutment angle αmaintains the relation α₂≦α≦α₁ regardless of the number of sheets ofpaper P stacked on the hopper 6. Therefore, the abutment angle α_(max)does not exceed the upper limit value α₁ and the abutment angle α_(min)does not fall below the lower limit value α₂ regardless of the number ofstacked sheets of paper P, so that the appropriate paper feed operationcan always be performed. In the embodiment, the feed direction length ofthe hopper 6 is about 130 mm and the swing angle of the hopper 6 isabout 10 deg. In this case, however, the swing angle 2 deg of the hopper6 until the top sheet of paper P is pressed against the paper feedroller 3 when a maximum number of sheets of paper are set is notcontained.

Next, the guide member 13 will be discussed. As shown in FIG. 6, oneguide member 13 comprises two smooth guide faces 13 a for guiding paperP downstream (see FIG. 7) at a predetermined interval in the widthdirection of paper P, and two guide members 13 each having the two guidefaces 13 a are placed at a predetermined interval in the width directionof paper P. The guide member 13 comprises an abutment face 13 bconnected to the guide face 13 a, which the tip of paper P stacked in aninclined attitude abuts roughly vertically (see FIG. 7). The abutmentface 13 b is formed by a circular arc (curved face) with the rotationshaft 6 a of the hopper 6 as the center, and the tip of paper P stackedon the hopper 6 in the inclined attitude slides over the abutment face13 b as the hopper 6 is rotated.

If the friction coefficient between the abutment face 13 b and the tipof paper P is large, it takes time in the press operation of pressingthe top sheet of paper P against the paper feed roller 3 by rotating thehopper 6 and the paper feed operation may be adversely affected. Thus,it is desirable that the friction coefficient should be low as much aspossible (for example, μ<0.3). Therefore, in the embodiment, the guidemembers are molded of resin using POM (polyoxymethylene) or AES(acrylonitrile-ethylene styrene) and further a lubricant is applied tothe abutment faces 13 b, whereby a low friction coefficient is provided.The separation pad holder 9 is also formed with an abutment face 9 bsimilar to the abutment face 13 b.

Next, as shown in FIGS. 5 and 6, the paper feed auxiliary roller 15 isplaced on the paper feed roller shaft 3 a between the paper feed roller3 and the transmission gear unit 17. The paper feed auxiliary roller 15is shaped roughly like a letter D as a side view in the axial directionof the paper feed roller shaft 3 a as described above. Like the paperfeed roller 3, the paper feed auxiliary roller 15 is made up of a rollermain body 15 c resin-molded integrally with the paper feed roller shaft3 a and a rubber member 15 b as an “elastic member” wound around theouter peripheral portion of the roller main body 15 c for preventingdamage to the print side of paper P.

The described paper feed auxiliary roller 15 serves the following twofunctions in the paper feed unit 1 according to the embodiment:

First, the paper feed auxiliary roller 15 serves the function ofregulating the feed attitude of paper P. That is, the paper feed roller3 and the separation pad 8 are provided in a pair and thus it isdesirable that only one pair of the paper feed roller 3 and theseparation pad 8 should be provided as in the embodiment to meet thedemand for cost reduction; to handle various sizes of paper P,particularly to handle paper P having a small width direction dimension,the pair of the paper feed roller 3 and the separation pad 8 is placedat a position to the 0 digit side (the right of FIG. 6).

However, the paper feed unit 1 feeds paper P with the paper P bent so asto become downward convex by the paper feed roller 3 as shown in FIG. 3.Thus, if the paper feed roller 3 is placed at a position to the 0 digitside, the paper P is not uniformly bent over the width direction,namely, the side of the paper P where the paper feed roller 3 is notdisposed (the left of FIG. 6) is not bent as compared with the side ofthe paper P where the paper feed roller 3 is disposed and accordingly itis feared that a difference may occur between the left and right advancedegrees at the paper P tip, causing a skew to occur. Therefore, thepaper feed auxiliary roller 15 is placed on the side where the paperfeed roller 3 is not disposed, thereby regulating the bend attitude ofthe paper P so that it becomes uniform for accomplishing the normalpaper feed operation.

The paper feed auxiliary roller 15 is shaped roughly like a letter D asa side view like the paper feed roller 3 and is formed in the samediameter as the paper feed roller 3, but the flat portion in the letterD shape is further cut as compared with that of the paper feed roller 3,as shown in FIG. 8A. As shown in the figure, the flat portion of thepaper feed auxiliary roller 15 is cut to the rotation center side (theside of the paper feed roller shaft 3 a) as compared with the flatportion of the paper feed roller 3 (for example, 4 mm relative to thediameter 48 mm of the paper feed roller 3, the paper feed auxiliaryroller 15).

The reason is as follows: When paper P is transported (at the printoperation time), the flat portion of the paper feed roller 3 (the paperfeed auxiliary roller 15) is opposed to the paper P as shown in FIG. 7to lessen the transport load (rotation load of the transport driveroller 162 (see FIG. 3)). Paper return levers 12 and 12 are disposedbelow the paper feed roller 3 as shown in FIG. 8A (also see FIG. 7) andthe paper P is a little warped by the paper feed roller 3 and the paperreturn levers 12 and 12 in a width direction view as shown in FIG. 8B.At this time, if the paper feed auxiliary roller 15 is of the same shapeas the paper feed roller 3, the paper P is warped further like a convexshape as indicted by the dashed line in FIG. 8B, and the disadvantage ofincreasing the transport load by the rigidity of the paper P andfriction of the paper feed roller 3, the paper feed auxiliary roller 15,and the paper return levers 12 occurs. Therefore, the shape of the paperfeed auxiliary roller 15 is made different from that of the paper feedroller 3 as described above, whereby unnecessary warpage is not given tothe paper P and an increase in the transport load is prevented.

By the way, as the paper P indicated by the phantom line in FIG. 6,A4-size paper is set in portrait orientation, and in the embodiment, thepaper feed roller 3 and the paper feed auxiliary roller 15 are placedequally matching the width dimension of the A4-size paper P as shown inthe figure. Therefore, the feed attitude of A4-size paper P generallyfrequently used can be regulated most uniformly and the effect of thepaper feed auxiliary roller 15 can be produced most efficiently.However, the disposition of the paper feed auxiliary roller 15 is notlimited to that in the embodiment and may be any position if theposition is a position for enabling the paper P to be fed normally,namely, the feed attitude of the paper P to be regulated.

Second, the paper feed auxiliary roller 15 serves the function as a“twist suppression member” for suppressing a twist of the paper feedroller shaft 3 a. That is, the paper feed roller shaft 3 a serves thefunction as the power transmission shaft for transmitting the rotationforce (power) given by the transmission gear unit 17 placed at the leftof the printer (the left of FIG. 6) to the hopper release device(described later) placed at the right of the printer (the right of FIG.6) as described above. Therefore, when the power is transmitted to thehopper release device or when the paper feed operation of the paper feedroller 3 is performed, a load occurs on the paper feed roller shaft 3 a,causing the paper feed roller shaft 3 a to be twisted. If the paper feedroller shaft 3 a is twisted, a phase shift occurs in the rotationoperation of the paper feed roller 3 or the operation of the hopperrelease device to which the power is supplied, and it is made impossibleto perform the normal paper feed operation and power transmission.Particularly, the paper feed roller 3 is placed at the position at adistance from the shaft end of the paper feed roller shaft 3 a to whichthe rotation force is given (the left of FIG. 6) and thus the paper feedroller 3 still more easily receives the effect of the twist.

However, the paper feed auxiliary roller 15 is provided on the paperfeed roller shaft 3 a, so that the twist is decreased in the portionwhere the paper feed auxiliary roller 15 is placed and therefore it ismade possible to lessen the above-described problem of the phase shiftoccurring accompanying the twist. Such a twist suppression section isadditionally placed at any other position whenever necessary, whereby itis made possible to provide the advantage furthermore. At the time, theshape need not be the same as that of the paper feed roller 3 and may beany if it has a larger diametric dimension than that of the paper feedroller shaft 3 a. In addition, in the embodiment, the paper feed rollershaft 3 a, the paper feed roller 3 (roller main body 3 c), and the paperfeed auxiliary roller 15 (roller main body 15 c) are molded in one pieceusing ABS resin, so that it is made possible to form the components atlow cost and provide the above-described twist suppression effectfurthermore. For example, if the paper feed auxiliary roller 15 and thepaper feed roller shaft 3 a are formed separately and the paper feedauxiliary roller 15 is attached to the paper feed roller shaft 3 a bybonding device, etc., it is made possible to provide predetermined twistsuppression effect by the bonding effect.

By the way, the rubber member 15 b is wound around the outer peripheralportion of the paper feed auxiliary roller 15 as described above. In theembodiment, the rubber member 15 b is made of EPDM (ethylene propylenerubber) like the rubber member 3 b wound around the outer peripheralportion of the paper feed roller 3; the EPDM comprises an additive addedto the EPDM of the rubber member 3 b described above, so that thetensile strength of the rubber member 15 b is improved. The reason whythe tensile strength of the rubber member 15 b wound around the paperfeed auxiliary roller 15 is improved more than the rubber member 3 bwound around the paper feed roller 3 is as follows:

To being with, it is desirable that an elastic member should be woundaround the outer peripheral portion of the paper feed auxiliary roller15 from the viewpoint of protection of the print side of paper P asdescribed above, but it is not desirable to use an elastic member of thesame width as the paper feed roller 3 from the view point of costreduction. However, if an elastic member having a smaller width thanthat of the paper feed roller 3 is used, the whole strength is degradedand the following problem occurs: The guide member 13 for smoothlyguiding the paper P downstream is placed at the position opposed to thepaper feed auxiliary roller 15 as shown in FIG. 7 and the paper feedauxiliary roller 15 is placed between the two guide faces 13 a and 13 aas shown in FIG. 6. Therefore, if multiple sheets of paper P are fed ata time in such a composition, the sheet bundle of the paper P issandwiched between the paper feed auxiliary roller 15 and the two guidefaces 13 a and 13 a, namely, a paper jam occurs.

If the paper feed unit 1 is configured to perform control so as to stopthe paper feed roller 3, for example, when a paper jam occurs, the drivemotor 169 (see FIG. 4) for rotating the paper feed roller 3 is in anenergized state and thus when the jammed paper bundle is drawn out, thepaper feed roller shaft 3 a does not rotate and therefore if the paperbundle is drawn out by force in the state, the rubber member 15 b may betorn.

Therefore, as the tensile strength of the rubber member 15 b woundaround the paper feed auxiliary roller 15 is improved, if a paper jamoccurs between the paper feed auxiliary roller 15 and the two guidefaces 13 a and 13 a and the jammed paper bundle is drawn out by force,the rubber member 15 b wound around the paper feed auxiliary roller 15can be prevented from being torn and at the same time, the widthdirection dimension is decreased, so that the cost can be reduced.

In the embodiment, the paper feed auxiliary roller 15 has a smallerwidth than the paper feed roller 3 as shown in FIG. 6, whereby the costof the rubber member 15 b is reduced and the space surrounding the paperfeed auxiliary roller 15 is saved and thus when the paper feed unit 1 isjoined to the carriage unit 120 (see FIG. 1), the flexibility ofplacement of the components of the carriage unit 120 is enhanced.However, the roller main body 15 c of the paper feed auxiliary roller 15has a width equal to or more than that of the paper feed roller 3 andthe width of the rubber member 15 b wound around the outer peripheralportion is unchanged, whereby the twist suppression effect of the paperfeed roller shaft 3 a described above can be provided furthermore and atthe same time, it is made possible to provide the various advantages ofthe paper feed auxiliary roller 15 described above. The elastic memberswound around the outer peripheral portions of the paper feed roller 3and the paper feed auxiliary roller 15 are not limited to those in theembodiment (rubber members (EPDM)); any other material, such as butylrubber, may be used. That is, any material may be used if it can providea friction coefficient for enabling paper P to be fed normally as theelastic member of the paper feed roller 3 or it protects the print sideof paper P and is at low cost as the elastic member of the paper feedauxiliary roller 15.

Next, paper press members 14 that can be rotated clockwise andcounterclockwise in FIG. 7 with a rotation shaft 14 a as the center areplaced at positions opposed to the hopper 6 in FIG. 7 (in theembodiment, two paper press members are placed with the paper feedroller 3 between although not shown). Each paper press member 14 servesa function of lightly pressing sheets of paper P stacked on the hopper 6from above under its own weight, thereby preventing floating up of thesheets of paper P stacked on the hopper 6. The paper return levers 12rotated by a cam mechanism (not shown) each with a rotation shaft 12 aas the center are placed below the hopper 6 (in the embodiment, twopaper return levers are placed with the paper feed roller 3 between (seeFIGS. 6 and 8B)). The paper return levers 12 serve the function ofreturning paper P staying in the proximity of the separation pad 8provided for preventing duplicate delivery of paper P to the top of thehopper 6 and performing the paper feed operation of the next sheet ofpaper P normally, as described above.

The description of the detailed configuration of the paper feed unit 1is now complete.

<Configuration of Hopper Release Device>

Next, the configuration of the hopper release device for rotating thehopper 6 in a direction in which the hopper 6 is brought away from thepaper feed roller 3 will be discussed with reference to FIGS. 10 to 13Band other accompanying drawings whenever necessary. FIG. 10 is apartially enlarged perspective view of the paper feed unit 1 and FIG. 11is a schematic drawing to show the action position of an external forceacting on the hopper 6. FIG. 12A is a front view of a rotary cam 20,FIG. 12B is a sectional view taken on line y-y in FIG. 12A, FIG. 13A isa front view of a cam lever holder 35, and FIG. 13B is a side view ofthe cam lever holder 35 (a z arrow view in FIG. 13A).

The hopper release device is placed on the right side of the paper feedunit 1 (the front of FIG. 5, the right of FIG. 6), as described above.In FIG. 5, a transmission gear 11 is attached to the right end of thepaper feed roller shaft 3 a, and the transmission gear 11 and a gearpart 25 (see FIG. 12B) formed on the rear of a rotary cam 20 attachedfor rotation by a rotation shaft 21 mesh with each other, whereby therotary cam 20 is rotated. That is, the rotary cam 20 is rotated withrotation of the paper feed roller 3, and the hopper release device doesnot have its own drive source and is formed at low cost. Thetransmission gear 11 meshes directly with the rotary cam 20 and has thesame number of teeth as the gear part 25. Therefore, as the paper feedroller 3 rotates once clockwise, the rotary cam 20 rotates oncecounterclockwise.

On the other hand, a cam lever 30 and a cam lever holder 35 that canswing with rotation of the rotary cam 20 are placed below the rotary cam20, and the hopper release device described below in detail isconfigured so as to perform the engagement operation in the order of therotary cam 20, the cam lever 30, and the cam lever holder 35. The hopperrelease device is configured so as to rotate a release bar 16 (see FIG.10) engaging the rear of the hopper 6 (the right of FIG. 7) by the swingoperation of the cam lever holder 35, thereby rotating the hopper 6. Thehopper release device has been outlined.

The structure and function of the release bar 16 placed on the rear ofthe hopper 6 will be discussed. As shown in FIG. 10, the release bar 16is shaped roughly like angular U and consists of a first shaft part 16 bextending in the length direction of the hopper 6 (width direction ofpaper P), a second shaft part 16 a extending vertically from one end ofthe first shaft part 16 b to the proximity of the helical compressionspring 7, and a third shaft part 16 c extending roughly parallel withthe second shaft part 16 a from an opposite end of the first shaft part16 b.

As shown in FIG. 7, the release bar 16 has the first shaft part 16 bjournaled by a bearing part 18 placed above a subframe 19 shaped like Vas a side view, whereby the second shaft part 16 a and the third shaftpart 16 c can be rotated clockwise and counterclockwise in FIG. 7 withthe first shaft part 16 b as a rotation shaft.

On the other hand, the hopper 6 is formed on the rear with an engagementpart 6 c (see FIG. 7) that the tip of the second shaft part 16 aengages, and the cam lever holder 35 described later in detail is formedwith a recess part 44 by a projection 38, as a “hopper action section”into which the folded tip of the third shaft part 16 c is fitted, asshown in FIGS. 13A and 13B. When the cam lever holder 35 is rotatedclockwise and counterclockwise in FIG. 13A, the release bar 16 isrotated with the first shaft part 16 b as a rotation shaft, whereby thehopper 6 is swung. This device that the cam lever holder 35, the camlever 30, and the rotary cam 20 make up “release bar rotation device”for rotating the release bar 16.

By the way, the disposition position of the engagement part of therelease bar 16 and the hopper 6, namely, the engagement part 16 c andthe placement position of the helical compression spring 7 are roughlythe same, as shown in FIGS. 7 and 10 and therefore the action point ofthe force given by the release bar 16 to the hopper 6 and the actionpoint of the force given by the helical compression spring 7 to thehopper 6 are placed at roughly the same position in a plan view of thehopper 6. Therefore, a bending moment scarcely occurs in the hopper 6and deformation of the hopper 6 is prevented, so that it is madepossible to maintain the normal paper feed operation.

More particularly, as shown in FIG. 11, the hopper 6 is made of aplate-like body long in the width direction of paper P and thus if theaction point of the force given by the release bar 16 (second shaft part16 a) to the hopper 6 (white arrow in FIG. 11) and the action point ofthe force given by the helical compression spring 7 to the hopper 6(black arrow in FIG. 11) do not match on the plane of the hopper 6(side-to-side direction of FIG. 11 and surface and back direction of theplane of the figure), a bending moment occurs in the hopper 6 andaccordingly the hopper 6 is bent temporarily or will be bent in thefuture. If the hopper 6 is thus bent, various defective conditions suchthat the maximum number of set sheets of paper P is decreased and that askew occurs when paper P is transported occur.

However, in the paper feed unit 1, as described above, the action pointof the force given by the release bar 16 to the hopper 6 and the actionpoint of the force given by the helical compression spring 7 to thehopper 6 are placed at roughly the same position on the plane of thehopper 6 as shown in FIG. 11. Therefore, a bending moment scarcelyoccurs in the hopper 6 and deformation of the hopper 6 is prevented, sothat it is made possible to maintain the normal paper feed operation,and the force action points match on the hopper 6 and thus thehigh-speed swing operation of the hopper 6 can be performed stably.

Next, the rotary cam 20, the cam lever 30, and the cam lever holder 35as the release bar rotation device for rotating the release bar 16 willbe discussed.

To being with, as shown in FIG. 12A, the rotary cam 20 is shaped like adisk rotating with a rotation shaft 21 (see FIG. 5) inserted into ashaft hole 21 a in a front view and comprises a stepwise cam part formedso as to protrude stepwise toward the shaft hole 21 a from the outerperiphery (the range indicated by area (1) in FIG. 12A). The stepwisecam part is made up of fan-shaped cams 22 a to 22 e each forming a fanshape in the front view for engaging the cam lever 30 on the outerperipheral surface. Formed contiguous with the fan-shaped cam 22 a is acam lever guide part consisting of a guide face 23 a and fan-shapedguide faces 23 b to 23 e for guiding the cam lever 30 to the outerperipheral surfaces of the fan-shaped cams 22 a to 22 e and guide slopes24 a to 24 c for guiding the cam lever 30 to the guide face 23 a and thefan-shaped guide faces 23 b to 23 e, the cam lever guide part forguiding the cam lever 30 to the outer peripheral surface of any of thefan-shaped cams (22 a to 22 e) corresponding to the stack amount ofsheets of paper P (the range indicated by area (2) in FIG. 12A).

The guide face 23 a and the fan-shaped guide faces 23 b to 23 e arepositioned to the inner peripheral side of the rotary cam 20 stepwisefrom the outer peripheral surfaces of the fan-shaped cams 22 a to 22 e,so that the cam lever 30, for example, on the fan-shaped guide face 23 cengages the outer peripheral surface of the fan-shaped cam 22 b as therotary cam 20 is rotated counterclockwise in FIG. 12A from the state.The fan-shaped guide faces 23 b to 23 e are formed so that phases (startpoints of circular arcs) differ spirally as shown in FIG. 12A.

The guide slopes 24 a to 24 c serve the function of guiding the camlever 30 positioned in a non-cam part 26 (described later) to the guideface 23 a and the fan-shaped guide faces 23 b to 23 e. The guide slope24 a protrudes gradually clockwise in the rotary cam 20 as shown in FIG.5 and becomes a diametrically uniform height (in FIG. 12B, the left ishigh side) and then is connected to the fan-shaped guide face 23 eroughly at the same height on the inner peripheral side and is connectedto the guide slope 24 b dropping to the fan-shaped guide faces 23 b, 23c, 23 d at lower positions than the fan-shaped guide face 23 e in thediametrical center and is connected to the guide slope 24 c dropping tothe fan-shaped guide face 23 a on the outer peripheral side.

Next, the non-cam part 26 made of a flat disk face is placed contiguouswith the fan-shaped cams 22 a to 22 e (the range indicated by area (3)in FIG. 12A). The non-cam part 26 does not restrain the cam lever 30 inthe diametric direction of the rotary cam 20 and therefore the cam leverin an engagement state with the fan-shaped cam 22 a positioned on theoutermost peripheral side, for example, is displaced toward the rotationcenter of the rotary cam 20 until the top sheet of paper P is pressedagainst the paper feed roller 3 by the urging force of the helicalcompression spring 7 shown in FIG. 7 when the rotary cam 20 is rotatedcounterclockwise in FIG. 12A from the engagement state of the cam lever30 with the fan-shaped cam 22 a and enters the area of the non-cam part26. In contrast, the cam lever 30 in the area of the non-cam part 26 isguided to the outer peripheral surface of the fan-shaped cam 22 apositioned on the outermost peripheral side while it is guided by a camface 26 a smoothly continued to the outer peripheral surface of thefan-shaped cam 22 a when the rotary cam 20 is rotated clockwise in FIG.12A from the state in which the cam lever 30 is in the area of thenon-cam part 26.

Next, in FIGS. 13A and 13B, the cam lever holder 35 is shaped like anarm consisting of an arm part 39 a extending from a shaft hole 40 intowhich a rotation shaft 36 (see FIG. 5) is inserted and an arm part 39 bdiverted from the arm part 39 a and extending slantingly upward, and isattached to the paper feed unit frame 2 for rotation with the shaft hole40 as the center. The cam lever holder 35 is provided with a spring hookpart 43 and the paper feed unit frame 2 is also provided with a similarspring hook part (not shown) and an extension spring 37 is placed on thespring hook parts (see FIG. 5). The extension spring 37 exerts such aspring force rotating the cam lever holder 35 clockwise in FIGS. 13A and13B, whereby the projection 38 is always in contact with the release bar16.

In FIG. 13A, as the cam lever holder 35 is rotated clockwise in thefigure, the release bar 16 (third shaft part 16 c) is rotatedcounterclockwise in the figure and accordingly the hopper 6 is rotatedin a direction in which it is brought away from the paper feed roller 3.At this time, the cam lever holder 35 rotates the hopper 6 against thespring force of the helical compression spring 7 (see FIG. 7). On theother hand, as the cam lever holder 35 is rotated counterclockwise inFIG. 13A, the release bar 16 (third shaft part 16 c) is rotatedclockwise in the figure and accordingly the hopper 6 is rotated in adirection in which it is pressed against the paper feed roller 3. Atthis time, the release bar 16 and the cam lever holder 35 are rotated bythe spring force of the helical compression spring 7 (see FIG. 7).

The cam lever 30 has a rotation shaft 32 journaled by bearing parts 41and 41 formed in the cam lever holder 35 and can be swung in the axialdirection of the rotary cam 20 as indicated by phantom lines in FIGS.12B and 13B. The cam lever 30 is provided with a spring hook part 33 andthe cam lever holder 35 is provided with a hole part 42 and a torsioncoil spring 31 is placed between the spring hook part 33 and the holepart 42. Therefore, the cam lever 30 is pulled to the rotary cam 20 bythe spring force of the torsion coil spring 31 and is always in contactwith the rotary cam 20.

The engagement operation of the rotary cam 20, the cam lever 30, and thecam lever holder 35 described above will be discussed. To begin with, inFIG. 12A, the case where the cam lever 30 is pressed against the outerperipheral surface of the fan-shaped cam 22 a as indicated by thephantom line and numeral 30 and the rotary cam 20 rotates once (360degrees) from the state will be discussed.

When the cam lever 30 is on the fan-shaped cam 22 a, the cam leverholder 35 is placed at a position where it is rotated most clockwise asseen in FIG. 13A, and therefore the hopper 6 is placed most away fromthe paper feed roller 3. When the rotary cam 20 is rotatedcounterclockwise in FIG. 12A, the cam lever 30 is detached from thefan-shaped cam 22 a, enters the area of the non-cam part 26 (area (3)),and is displaced toward the rotation center of the rotary cam 20. As thecam lever 30 is thus displaced in the center direction of the rotary cam20, the cam lever holder 35 is rotated counterclockwise in FIG. 13A andthus the hopper 6 is rotated in the direction in which it is pressedagainst the paper feed roller 3 by the urging force of the helicalcompression spring 7.

Here, if the stack amount of sheets of paper P set on the hopper 6 islarge, the swing angle of the hopper 6 is lessened. Therefore, in thiscase, the cam lever 30 is small displaced toward the rotation center ofthe rotary cam 20 if it is detached from the fan-shaped cam 22 a. On theother hand, if the stack amount of sheets of paper P set on the hopper 6is small, the swing angle of the hopper 6 is increased. Therefore, inthis case, the cam lever 30 is largely displaced toward the rotationcenter of the rotary cam 20 after it is detached from the fan-shaped cam22 a.

As the rotary cam 20 is further rotated counterclockwise in FIG. 12A,the cam lever 30 enters the cam lever guide part (area (2)) and startsto engage the guide slope 24 a. At this time, although the cam lever 30is not displaced in the diametric direction of the rotary cam 20, it isswung in the axial direction of the rotary cam 20 (see FIG. 12B) and isguided to any of the fan-shaped guide face 23 e, the guide slope 24 b(and then the fan-shaped guide face 23 b-23 d), or the guide slope 24 c(and then the guide face 23 a).

Here, what position the cam lever 30 is at in the diametric direction ofthe rotary cam 20 depends on the stack amount of sheets of paper P seton the hopper 6 as described above and thus which of the fan-shapedguide face 23 e, the guide slope 24 b (and then the fan-shaped guideface 23 b-23 d), and the guide slope 24 c (and then the guide face 23 a)the cam lever 30 is guided to depends on the stack amount of sheets ofpaper P. Therefore, for example, if the stack amount of sheets of paperP is minimum, the cam lever 30 is guided to the fan-shaped guide face 23e; if the stack amount of sheets of paper P is maximum, the cam lever 30is guided to the guide slope 24 c (and then the guide face 23 a).

Next, as the rotary cam 20 is further rotated, the cam lever 30 climbsto the outer peripheral surface of the fan-shaped cam initiallypositioned on the outer peripheral side (fan-shaped cam 22 a-22 e) fromthe diametric position in the rotary cam 20 at the time. That is, thecam lever 30 is small displaced in the diametric direction of the rotarycam 20 (direction toward the outer periphery from the rotation center ofthe rotary cam 20, and the cam lever holder 35 is small rotatedclockwise in FIG. 13A. Therefore, the hopper 6 is a little swung in thedirection in which it is brought away from the paper feed roller 3.Thus, the top sheet of paper P pressed against the paper feed roller 3is placed in a state in which it is a little away from the paper feedroller 3 (free state).

The engagement operation of the rotary cam 20, the cam lever 30, and thecam lever holder 35 has been described. Thus, the hopper release devicehas three modes of “large release mode” for rotating the hopper 6 so asto bring the hopper 6 most away from the paper feed roller 3 (state inwhich the cam lever 30 engages the outer peripheral surface of thefan-shaped cam 22 a positioned on the outermost peripheral side),“non-release mode” for pressing the hopper 6 against the paper feedroller 3 (state in which the cam lever 30 is in the non-cam part 26(area (3)) or the cam lever guide part (area (2)), and “small releasemode” for rotating and holding the hopper 6 so that the top sheet ofpaper P and the paper feed roller 3 are a little away from each other(state in which the cam lever 30 is moved from area (2) to area (1)),and can execute any of the modes as desired by controlling rotation ofthe rotary cam 20 (paper feed roller shaft 3 a).

The number of steps of the stepwise cam parts (fan-shaped cams 22 a to22 e) formed on the rotary cam 20 is five in the embodiment. However, asseen from the description made above, as the number of steps isincreased, it is made possible to control the hopper 6 more finely inresponse to the stack amount of sheets of paper P, needless to say.

Next, the actual paper feed control in the paper feed unit 1 and theadvantages of the hopper release device will be discussed with referenceto FIGS. 14 to 22B. FIG. 14 is a timing chart to show the operationtransition of the paper feed roller 3, the cam lever 30, and the hopper6 and FIGS. 15A to 22B are schematic representations to show the stateof the paper feed roller 3, the cam lever 30, and the hopper 6 at thetimings in the timing chart of FIG. 14; (A) mainly shows the positionalrelationship between the paper feed roller 3 and the hopper 6 and (B)mainly shows the engagement state of the cam lever 30 and the rotary cam20.

AREAS (1), (2), and (3) shown in FIG. 14 correspond to the areas of therotary cam 20 shown in FIG. 12A. Numerals of the cam lever 30 shown onthe chart denote the fan-shaped cams 22 a to 22 e or the guide face 23 aand the fan-shaped guide faces (23 b to 23 e) that the cam lever 30engages. Further, NON-RELEASE of the hopper 6 device the hopper 6 in thestate in which paper P set on the hopper 6 is pressed against the paperfeed roller 3 according to the non-release mode; SMALL RELEASE devicethe hopper 6 in the state in which the top sheet of paper P set on thehopper 6 is a little away from the paper feed roller 3 according to thesmall release mode; and LARGE RELEASE device the hopper 6 in the statein which the hopper 6 is most away from the paper feed roller 3according to the large release mode. FORWARD ROTATION of the paper feedroller 3 device that the paper feed roller 3 is rotated clockwise inFIGS. 15A to 22B, and the rotary cam 20 is rotated counterclockwise inthe figures with the forward rotation of the paper feed roller 3.

To begin with, at the paper feed start time, the cam lever 30 is on thefan-shaped cam 22 a (FIG. 15B), the hopper 6 is most away from the paperfeed roller 3 (FIG. 15A), and in the state, the paper feed unit 1 is ina nonoperating state in which paper P can be set. When the paper feedroller 3 is forward rotated to perform the paper feed operation from thestate, the rotary cam 20 is rotated counterclockwise in the figure,whereby the cam lever 30 is detached from the fan-shaped cam 22 a andenters the area of the non-cam part 26 (area (3)) (FIG. 16B) and thepaper P set on the hopper 6 is pressed against the paper feed roller 3(FIG. 16A). That is, the hopper release device executes the non-releasemode (section a in FIG. 14). As the paper feed roller 3 is rotated,feeding the top sheet of paper P is started.

Next, as the paper feed roller 3 is further forward rotated, the camlever 30 starts to engage the guide slope 24 a (cam lever guide part:Area (2)) and is guided to either the guide face 23 a or the fan-shapedguide face 23 b-23 d in response to the stack amount of sheets of paperP set on the hopper 6 (FIG. 17B: In the embodiment, guided to thefan-shaped guide face 23 c via the guide slope 24 b). At this time, thepaper P set on the hopper 6 remains pressed against the paper feedroller 3 (non-release state) (sections b and c in FIG. 14).

Next, as the paper feed roller 3 is further forward rotated, the camlever 30 climbs to the outer peripheral surface of the fan-shaped cam 22c from the fan-shaped guide face 23 c (FIG. 18B) and the hopper 6 is alittle rotated in the direction in which it is brought away from thepaper feed roller 3 and thus the paper P is placed in a state in whichit is a little away from the paper feed roller 3 (FIGS. 19A and 19B).That is, the hopper release device executes the small release mode(section d in FIG. 14).

The paper feed roller 3 rotates once (360 degrees) and rotation of thepaper feed roller 3 is stopped in a state in which the flat portion ofthe shape roughly like a letter D as the side view is opposed to theseparation pad 8 for preventing a transport load from occurring on thepaper P during the print operation (transport operation). In this state,a wait is made until feeding the next sheet of paper P is started (FIGS.19A and 19B) (section e in FIG. 14). That is, if a feed job of the nextand later sheets of paper P is left, the hopper release device does notexecute the large release mode of placing the hopper 6 most away fromthe paper feed roller 3 after the termination of the paper feedoperation of one sheet of paper P and executes the small release modefor placing the top sheet of paper P a little away from the paper feedroller 3 after the termination of the paper feed operation of paper P.When the next sheet of paper P is fed, it is made possible for thehopper 6 to press the paper P against the paper feed roller 3 at aslight swing angle.

Next, if a feed job of another sheet of paper P does not exist uponcompletion of all print operation, the hopper release device executesthe large release mode and makes a transition to a nonoperating state.More particularly, the hopper release device makes a transition tosection f after the termination of section e in FIG. 14 (after thetermination of the print operation). In the section f, the paper feedroller 3 is forward rotated, whereby the cam lever 30 is once detachedfrom the fan-shaped cam 22 c and is induced to the non-cam part 26 (FIG.20B) and from the state, the paper feed roller 3 is reversely rotated,whereby the cam lever 30 is guided to the outer peripheral surface ofthe fan-shaped cam 22 a (FIG. 21B) and the hopper 6 is rotated so thatit is brought most away from the paper feed roller 3. That is, the largerelease mode is executed (FIGS. 22A and 22B).

Here, the paper feed roller 3 is forward rotated, whereby the cam lever30 is once detached from the fan-shaped cam 22 c and is induced to thenon-cam part 26. However, the cam lever 30 can also be induced to thenon-campart 26 by reversely rotating the paper feed roller 3 (rotatingthe rotary cam 20 clockwise in the figure). In this case, the paper feedroller 3 is once rotated reversely from the state in which the cam lever30 is on the fan-shaped cam 22 c, whereby it is made possible to executethe large release mode.

As described above, if a feed job of feeding the next and later sheetsof paper P is left after the termination of the paper feed operation ofthe top sheet of paper P, the hopper release device executes the smallrelease mode, so that it is made possible to minimize the swing range(swing angle) of the hopper 6 to feed the next sheet of paper P and thusit is made possible to decrease noise occurring when the hopper 6 isswung and execute the high-speed paper feed operation (repeated paperfeed).

The hopper 6 is rotated in the direction in which it is pressed againstthe paper feed roller 3 by the helical compression spring 7. Since thehopper 6 is rotated in the direction through the release bar 16restrained by the cam lever holder 35, the paper P stacked on the hopper6 does not collide with the paper feed roller 3 vigorously by the springforce of the helical compression spring 7 and thus it is made possibleto prevent defective conditions such as uneven sheets of paper P andwrinkling of paper P.

By the way, referring again to FIG. 7, the tip of paper P stacked on thehopper 6 slides on the guide face 13 a of the guide member 13 when thehopper 6 is swung, and thus if the friction coefficient between theguide face 13 a and the tip of paper P is large, smooth paper feedoperation cannot be performed if the swing range (swing angle) of thehopper 6 is minimized as described above. Therefore, a lubricant isapplied to the guide face 13 a in the embodiment, whereby the frictioncoefficient is made low (in the embodiment, μ<0.3), so that the smoothpaper feed operation can be performed reliably. However, the followingcontrol is performed in the paper feed operation sequence, whereby it ismade possible to overcome the defective conditions at the paper feedoperation time and provide the normal print quality more reliably.

To begin with, in FIG. 7, paper P fed by the paper feed roller 3 passesthrough the detector 136 a of the paper detector 136 and then is nippedbetween the transport drive roller 162 and the transport driven roller163. After the paper P is nipped between the two rollers, a given amountof start locating control is performed and print on the paper P isstarted. To perform the given amount of start locating control, uponreception of a passage detection signal of the paper P tip from thepaper detector 136, the transport drive roller 162 may be rotated asmuch as predetermined phase based on the signal reception timing.

On the other hand, FIG. 14 shows the relationship between the timing atwhich the paper detector 136 detects the passage of the paper P tip andthe timing at which the paper P tip arrives at the nip point between thetransport drive roller 162 and the transport driven roller 163 and thestate of the hopper 6. That is, at point I indicated by symbol I, thepaper P tip passes through the detector 136 a of the paper detector 136and at point indicated by symbol II, the paper P tip arrives at the nippoint between the transport drive roller 162 and the transport drivenroller 163.

However, if the swing operation of the hopper 6 is not smoothlyperformed and the timing at which the top sheet of paper P is pressedagainst the paper feed roller 3 is delayed, it is feared that the pointsI and II may shift to points I′ and II′ shown in FIG. 14. Then, it isfeared that the point at which the hopper 6 is switched from thenon-release state to the small release state may be contained betweenthe points I′ and II′, namely, the small release mode may be executed.

When the hopper 6 executes the small release mode, the cam lever 30climbs from the small-diameter cam part 23 to the large-diameter campart 22 as described above and thus at this time, a rotation load isimposed on the paper feed roller shaft 3 a of the rotation shaft of therotary cam 20 and accordingly the paper feed roller shaft 3 a istwisted. If the paper feed roller shaft 3 a is thus twisted, the feedamount of paper P is decreased accordingly.

However, when the start locating amount of paper P from the nip pointbetween the transport drive roller 162 and the transport driven roller163 is controlled based on the timing at which the passage detectionsignal of the paper P tip is received from the paper detector 136 asdescribed above, if the timing at which the top sheet of paper P ispressed against the paper feed roller 3 is delayed and thus the feedamount of paper P is decreased as the paper feed roller shaft 3 a istwisted between the points I′ and II′ as described above, the timing atwhich the paper P tip arrives at the nip point between the transportdrive roller 162 and the transport driven roller 163 is delayed andaccordingly the objective start locating amount may not be provided.This particularly becomes a problem because the swing angle of thehopper 6 reaches the maximum in the first sheet of paper P when anonoperating job sequence is started with the top sheet of paper Ppressed by the hopper 6 which is in the large release state (the paperfeed unit 1 is in a nonoperating state) and executes the non-releasemode from the large release state.

Then, for example, skew removal in so-called bite and ejection technique(in which the paper P tip is once bitten between the transport driveroller 162 and the transport driven roller 163 and then is ejectedupstream, thereby removing skew) is performed only for the first sheetof paper P when the paper feed job sequence is started, whereby theproblem of insufficient start locating amount as described above can besolved. A similar advantage can also be provided by making powerful theurging force of the urging device of the hopper 6 (in the embodiment,the helical compression spring 7) and making more reliable the rotationof the hopper 6 in the direction in which the hopper 6 is pressedagainst the paper feed roller 3.

FIG. 3 shows, in a recording apparatus comprising a paper feeder whereina plurality of single sheets of paper can be set, a paper deliverydevice for transporting paper fed from the paper feeder to a recorder,and a control unit for controlling operation of the paper feeder and thepaper delivery device, the control unit which comprises a skew removalexecution mode of only the first sheet of paper where the paper tip isbitten into a paper delivery roller forming a part of the paper deliverydevice and then the paper delivery roller is reversely rotated forejecting the paper tip for the first sheet of paper at the start ofrecording and then forward rotating the paper delivery roller fordelivering the sheet of paper whose skew is removed to the recorder anddelivering the second and later sheets of paper to a record area withoutexecuting the skew removal. The control unit comprises two or more ofthe paper feed modes (skew removal execution mode of the first sheet ofpaper only, skew removal mode, skew removal suppression mode, and speedchange mode) in the recording apparatus according to any one of claims 1to 5. The control unit outputs a control signal to the drive motor 169for executing each mode.

As described above, according to the invention, noise occurring when thehopper is swung can be decreased, high-speed paper feed operation can beperformed, and throughput can be enhanced.

Although the invention has been described in its preferred form with acertain degree of particularity, obviously many changes and variationsare possible therein. It is therefore to be understood that the presentinvention may be practiced than as specifically described herein withoutdeparting from scope and the spirit thereof.

1. A recording apparatus comprising: a paper feeder configured to set astack, comprising a plurality of single sheets of paper having the samethickness, therein; a paper delivery device having a paper deliveryroller for transporting a sheet of paper fed from said paper feeder to arecorder; and a control unit for controlling operation of said paperfeeder and said paper delivery device; wherein said paper feeder andpaper delivery device are configured to conduct a skew removal such thata paper tip of a sheet of paper fed from said paper feeder is oncebitten into the paper delivery roller and then ejected therefrom byreversely rotating said paper delivery roller before delivering thesheet of paper to the recorder by forwardly rotating the paper deliveryroller; and wherein said control unit controls feeding of the stackaccording to a skew removal execution mode, wherein the skew removalexecution mode controls feeding of the stack so that the skew removal isexecuted on only a first sheet of paper to a paper tip of the firstsheet of paper which is firstly fed by the paper feeder at a start of arecording operation of the apparatus and later sheets of paper aredelivered to the recorder without executing the skew removal.
 2. Therecording apparatus according to claim 1, where said paper feederincludes a paper feed roller for feeding one of the sheets of paper byrotating and a hopper for pushing up and pressing the sheets of paperagainst the paper feed roller, and the hopper is configured to push upthe first sheet of paper at the start of recording operation at a firststroke and to push up the later sheets of paper at a second stroke whichis smaller than the first stroke.
 3. The recording apparatus accordingto claim 2, wherein said second stroke is variable in accordance with anamount of the plurality of single sheets of paper in the paper feeder.